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<h3>Strange results?</h3>

<p>Strange (but correct) results may be obtained in some cases:</p>
<ul>
<li><p><b>Fraction diagrams for components that may have negative concentrations:</b> 
		When requesting a fraction diagram for <nobr>H<sup>+</sup>,</nobr> the plot
    has <nobr><i>Y</i>-axis</nobr> limits between 0 and 1 (0% to <nobr>100%).</nobr>
    However, negative values, or even values &gt;1 are possible. Consider the
		definition of fraction of <nobr>H<sup>+</sup>,</nobr> <nobr>&#945;(<i>i</i>),</nobr> 
    bound to the different species in the system
    <nobr>H<sup>+</sup>/HCO<sub>3</sub><sup>&#8722;</sup>:</nobr>
		<table cellspacing="0" cellpadding="0" border="0">
			<tr valign="baseline"> <td><tt>&nbsp;&nbsp;</tt></td>
					<td><nobr>HCO<sub>3</sub><sup>&#8722;</sup> &#8722; H<sup>+</sup>
									&#8596;
									CO<sub>3</sub><sup>2&#8722;</sup></nobr></td>
					<td><tt>&nbsp;</tt></td>
					<td><nobr>&#945;(CO<sub>3</sub><sup>2&#8722;</sup>) = &#8722; [CO<sub>3</sub><sup>2&#8722;</sup>]/[H<sup>+</sup>]<sub>TOT</sub></nobr></td>
					</tr>
			  <tr valign="baseline"> <td></td>
					<td><nobr>HCO<sub>3</sub><sup>&#8722;</sup>  + H<sup>+</sup>
									&#8596;
                  H<sub>2</sub>CO<sub>3</sub></nobr></td>
					<td></td>
					<td><nobr>&#945;(H<sub>2</sub>CO<sub>3</sub>) = [H<sub>2</sub>CO<sub>3</sub>]/[H<sup>+</sup>]<sub>TOT</sub></nobr></td>
					</tr>
			  <tr valign="baseline"> <td></td>
					<td><nobr>H<sub>2</sub>O  &#8722; H<sup>+</sup>
              &#8596; OH<sup>&#8722;</sup></nobr></td>
					<td></td>
					<td><nobr>&#945;(OH<sup>&#8722;</sup>) = &#8722;[OH<sup>&#8722;</sup>]/[H<sup>+</sup>]<sub>TOT</sub></nobr></td>
					</tr>
				</table>
	  the value of <nobr>[H<sup>+</sup>]<sub>TOT</sub></nobr> (the total concentration
	  of <nobr>H<sup>+</sup>)</nobr> might be positive (in acid solutions) or negative
	  (in alkaline solutions). Therefore in a fraction diagram for the component
	  <nobr>&#147;H<sup>+</sup>&#148;,</nobr> the fraction values might be negative
	  or even larger than&nbsp;one!</p></li>
<li><p><b>Activity ratio diagrams:</b> a diagram that might seem strange (but correct),
		is the case of the example input file <nobr>EX7.DAT,</nobr> where the activity
    ratio for the solid phase <nobr>Cu(OH)<sub>2</sub>(s)</nobr> is greatest,
    but the activity of the solid is nevertheless less than one, and the solid
    is <u>not</u> present at equilibrium.</p></li>
<li><p><b>Predominance area diagrams:</b> in some special cases, two solid phases
		might coexist containing exactly the same amount of metal. In that case, no solid
		predominates, and some parts of the lines will be missing in the predominance
		area diagram. For example, on a system with <nobr>H<sup>+</sup>,</nobr>
		<nobr>e&#8722;,</nobr> <nobr>Fe<sup>2+</sup>,</nobr> <nobr>Ni<sup>2+</sup></nobr> and
		<nobr>Cr<sup>3+</sup>,</nobr>  <nobr>Fe<sub>3</sub>O<sub>4</sub>(s)</nobr> and
		<nobr>NiFe<sub>2</sub>O<sub>4</sub>(s)</nobr> might co-exist.<p></li>
</ul>

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